1. Field of the Invention
The present invention relates generally to an adjustable hinged door closer, and more particularly to an innovative door closer fitted with double-threaded regulator that can easily change spring compression for regulating rapidly and accurately the closing and restoring force of the door.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
A door closer is generally mounted onto the rotary shaft seat of a revolving door to control the closing speed of door panel.
As for the previous structure of the door closer, the opening or closing force of the door body cannot be regulated. That is to say, a spring mechanism is mounted into the door body such that the spring is compressed to accumulate energy and then released so as to control the closing speed via the energy and resistance. Such a typical door closer is available with several opening and closing forces depending on the size of the door body and the occasions. But there are some shortcomings, such as excessive opening resistance or insufficient closing force, which still exist due to different occasions and objects.
For the aforementioned reasons, an adjustable door closer has been developed, e.g. U.S. Pat. No. 5,666,692 discloses an adjustable door closer. This prior art has shortcomings. First, the stretching screw thereof is of a single-screw thread that requires a great number of turns for regulation, so time-consuming fine-tuning still exists during actual operation. Second, the stretching screw thereof is installed obliquely such that it has an included angle with internal tension member. With the increase of the rotating turns of the stretching screw, the tension member yields reverse tensile force for the stretching screw, so linear deformation max occur, leading to oil leakage arising from the gap between the stretching screw and the assembly hole. Also, the interior of the stretching screw must be mated with relevant members within the main body of the door closer, leading to difficult assembly, greater chances for defects and manufacturing costs.
There is also U.S. Pat. No. 6,493,904B1, by the present inventor, which has other shortcomings. First, the regulating members must be connected with the relevant members within the main body of the door closer, leading to difficult assembly, greater chances for defects and manufacturing costs. Also, the regulating lever is easily broken due to thermal treatment, making it difficult for repair.
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement in the art to provide an improved structure that can significantly improve efficacy.
Therefore, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.